source code checkin

src/ServerManager.Common/ViewModel/NullableValue.cs

@@ -0,0 +1,120 @@
+using ServerManagerTool.Common.Interfaces;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace ServerManagerTool.Common.Model
+{
+    public class NullableValue<T> : INotifyPropertyChanged, INullableValue
+    {
+        public NullableValue()
+        {
+            HasValue = false;
+            Value = default;
+            DefaultValue = default;
+        }
+
+        public NullableValue(T value)
+        {
+            HasValue = value != null;
+            Value = value;
+            DefaultValue = value;
+        }
+
+        public NullableValue(bool hasValue, T value)
+        {
+            HasValue = hasValue;
+            Value = value;
+            DefaultValue = value;
+        }
+
+        public NullableValue(T value, T defaultValue)
+            : this(value)
+        {
+            DefaultValue = defaultValue;
+        }
+
+        public NullableValue(bool hasValue, T value, T defaultValue)
+            : this(hasValue, value)
+        {
+            DefaultValue = defaultValue;
+        }
+
+        public bool HasValue
+        {
+            get { return Get<bool>(); }
+            set { Set(value); }
+        }
+
+        public T DefaultValue
+        {
+            get { return Get<T>(); }
+            set { Set(value); }
+        }
+
+        public T Value
+        {
+            get { return Get<T>(); }
+            set { Set(value); }
+        }
+
+        public INullableValue Clone() => new NullableValue<T>(HasValue, Value, DefaultValue);
+
+        public bool Equals(T value) => HasValue && object.Equals(value, Value);
+
+        public NullableValue<T> SetValue(T value)
+        {
+            HasValue = true;
+            Value = value;
+            return this;
+        }
+
+        public NullableValue<T> SetValue(bool hasValue, T value)
+        {
+            HasValue = hasValue;
+            Value = value;
+            return this;
+        }
+
+        public void SetValue(object value)
+        {
+            if (value != null && value is NullableValue<T>)
+            {
+                HasValue = ((NullableValue<T>)value).HasValue;
+                Value = ((NullableValue<T>)value).Value;
+                DefaultValue = ((NullableValue<T>)value).DefaultValue;
+            }
+        }
+
+        public override string ToString() => HasValue ? Value.ToString() : string.Empty;
+
+        #region INotifyPropertyChanged
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        private Dictionary<string, object> _properties = new Dictionary<string, object>();
+
+        protected T2 Get<T2>([CallerMemberName] string name = null)
+        {
+            object value = null;
+            if (_properties?.TryGetValue(name, out value) ?? false)
+                return value == null ? default : (T2)value;
+            return default;
+        }
+
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+
+        protected void Set<T2>(T2 value, [CallerMemberName] string name = null)
+        {
+            if (Equals(value, Get<T2>(name)))
+                return;
+            if (_properties == null)
+                _properties = new Dictionary<string, object>();
+            _properties[name] = value;
+            OnPropertyChanged(name);
+        }
+        #endregion
+    }
+}